#include <stdio.h>
#define N 100

void main()
	{
	 int year;
	 int p;

	 for(;;)
		{
		 printf("\nPlease input a year:");
		 scanf("%d",&year);
		 if(year<0) break;
		 if((year%4==0 && year%100!=0)||(year%400==0)) p=1;
		 else p=0;

		 if(p)
			printf("%d is a right year.",year);
		 else
			printf("\n%d is not a right year.",year);
		 }
	 }